The engine most often used in automobiles today is the conventional four-stroke Otto cycle engine. The engine output is usually varied by means of a butterfly throttle which controls the amount of air or fuel-air mixture inducted into the engine. A butterfly throttle acts as a restrictor and produces a pressure drop which constitutes an energy loss. At steady cruising speeds, when the engine is turning over rapidly, and the accelerator pedal is only partially depressed, this energy loss is significant.
In order to recover the energy which would be lost at a butterfly valve, in the instant invention the amount of air or fuel-air charge inducted into the engine is controlled by a blower which acts as a metering pump during a subcharging mode and acts as a supercharger during a supercharging mode.
The blower is driven from the engine by means of a variable speed hydraulic transmission, the speed ratio of which is controlled by the accellerator pedal. Thus, when the accelerator pedal is depressed so as to call for more power, the speed ratio of the variable speed hydraulic transmission changes to accelerate the blower, thereby inducting more air or fuel-air charge into the engine.
Since it takes a few moments for the blower to increase its speed, in order to provide quick acceleration, the blower is temporarily shunted by a performance by-pass duct, normally closed by a performance valve. The performance valve opens momentarily when the accelerator pedal is tromped on, thereby permitting the engine to increase its speed rapidly, without throttling by the blower. As soon as the blower has come up to the speed dictated by the position of the accelerator pedal, the performance valve closes.
The direction of power flow, through the variable speed hydraulic transmission, reverses when there is a change back and forth between the supercharging and the subcharging mode. However, the engine and blower always turn in the same direction, so that the motion of oil through certain portions of the hydraulic circuit necessarily also is in a constant direction. The conditions of the two preceeding sentences can cause operating troubles, which are avoided by introducing valving means into the hydraulic circuit to automatically switch the hydraulic circuit so that the portion thereof which acts as a pump is always directly connected to the portion thereof which acts as a motor. This avoids significant negative oil pressures in the pump circuit.
Combined with the novel engine is a variable compression ratio means and water feeding means, to provide cleaner burning, better running, and lower emissions over the range of speeds and loadings encountered.